In recent years, in the field of digital equipment such as digital household electrical appliances, personal computers, mobile phones, automobile applications, and white goods, there is an increasing need to improve security by remote diagnosis via a network and to improve system security by self-diagnosis. The above-described needs have been taken into consideration because of the necessity of system monitoring, protection of personal information and the like in terms of security. Furthermore, these techniques will be incorporated in devices as an encryption function and an authentication function for personal/system devices in the field of digital contents such as network contents distribution, digital broadcasting, and media contents service.
Implementing the above-described techniques requires a semiconductor chip that can be replaced as an alternative to a security chip, a system controller and the like incorporated into devices such as digital household electrical appliances, white goods, automobile applications, and high-performance mobile phones; and also that allows security enhancement by other existing contents encryption techniques, secure storage techniques and the like.
For example, in order to protect intellectual property rights, personal information, corporate information and the like in devices of information home appliances, white goods, automobile applications and the like, it is necessary to simultaneously and safely perform user information processing, system safety checks, settlement processing, if needed, and the like including data processing via a network. This requires implementation of a secure function that can withstand attacks by current monitoring, data row monitoring and the like.
Furthermore, in order to prevent leakage of encryption keys, code modification allowing a settlement part to be passed, and the like, it is necessary to implement an accounting function used when decrypting the contents by common key encryption with a programmable device having a self-dynamic logic reconfiguration function. As techniques related to the foregoing, Patent Documents 1-3 disclose the inventions as described below.
According to the invention disclosed in Japanese Patent Laying-Open No. 10-093422 (Patent Document 1), in the programmable logic circuit configured by a plurality of programmable logic cells providing a function of a logic function, a flip-flop, a wiring switch and the like, the logic cells are configured to simultaneously provide one function, in which the circuit implementing each function of the logic cells shares circuit resources such as a memory and a multiplexer. Consequently, circuit functions required by the circuit implemented on the programmable logic circuit can be efficiently implemented even though they are unbalanced, which allows effective use of circuit resources of the programmable logic circuit.
According to the invention disclosed in Japanese Patent Laying-Open No. 2000-232162 (Patent Document 2), in the case where a basic cell including a storage circuit, a readout circuit and a wiring connection switch is functioned as programmable logic means, the resource used when it is functioned as programmable connection means is utilized. Furthermore, a part of the connection line between the cells is twisted to ensure input/output connection also when cells having the same configuration are consecutively arranged. In addition, an input/output signal line at the time when the programmable logic means is applied is configured to be connectable within the cell, to thereby allow implementation of a feedback loop within the cell.
According to the invention disclosed in Japanese Patent Laying-Open No. 2005-158815 (Patent Document 3), a plurality of basic cells having logic blocks performing a logical operation are arranged in a matrix form. Each of the basic cells has a switch block for determining the connection relationship with the basic cells other than itself based on the given connection information. Thus, a part of the network made of regularly connected wiring tracks is replaced with a shortcut wiring track directly connecting the basic cells together which are randomly selected with a predetermined probability p, to construct a wiring network in a manner of a small-world network that allows a desired wiring route to be implemented by using only a small number of switch blocks.    Patent Document 1: Japanese Patent Laying-Open No. 10-093422    Patent Document 2: Japanese Patent Laying-Open No. 2000-232162    Patent Document 3: Japanese Patent Laying-Open No. 2005-158815